Portable car ramps are used for increasing vertical clearance beneath a vehicle having its wheels otherwise supported on a flat horizontal garage floor, driveway, or like support medium, so that a worker can repair, or service the vehicle from the underside thereof.
A typical portable car ramp will have bottom structure that can be rested in a stable manner on the support medium, a generally level wheel run extended substantially parallel to but elevated above the support medium, and an inclined wheel run extended between one end of the elevated wheel run and the support medium. The vehicle wheel can be rolled up the inclined run to the elevated run, and along it until restrained by a stop adjacent the opposite run end.
Popular portable car ramps might be about a foot wide, three to six feet long, and provide vertical wheel lifts between possibly six and fifteen inches with the inclined runs pitched between possibly ten and twenty five degrees.
Both sides of the vehicle frame can be elevated if two like car ramps are used, where both front wheels or both rear wheels can then be simultaneously rolled up the respective ramps and onto the respective elevated runs. To stabilize any vehicle supported on the ramps, a vehicle wheel yet on the support medium can be blocked.
One problem associated with car ramp use is that when the wheel weight is on the inclined run, particularly when the wheel is being rolled up the inclined run, horizontal vector forces are generated against the ramp tending to slide it along the support medium in the direction away from the vehicle. When severe sliding tendency exists, ramp bracing by external devices might be necessary.
However, permitting some car ramp sliding along the support medium might be beneficial, to reduce the possibility of the rolling wheel hitting and rolling over a nor-yielding end stop and rolling then off of the ramp.
A further drawback of many known car ramps is their bulky size and/or heavy weight, making it difficult to move them about during use and/or to store them.